Temperature Dependence of Thermal Expansion and Infrared Lattice Vibrational Mode of Nickel Oxide

Abstract

The lattice parameter of NiO from 105 K to 813 K has been measured using the X-ray diffraction technique. An orthogonal polynomial of second-order with least square error approximation is fitted to the lattice parameter versus temperature data to obtain the thermal expansion coefficient, α. The high temperature values of α have been found to be in close agreement with the measurements of earlier workers, using an automatic recording dialatometer.
Experimental investigations have also been made of the infrared transmission spectrum of NiO in the region of fundamental lattice absorption between 293 K and 500 K, using a Beckman IR-12 spectrophotometer. The shift in the long-wavelength optical mode frequency with temperature is discussed in terms of volume and other anharmonic effects employing the present values of α and is found to agree qualitatively with the theory of Maradudin and Fein.